Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

First known case of zebra shark switching to asexual reproduction

The story begins in 1999 when Leonie, a zebra shark (aka a leopard shark in Australia), was captured from the wild. In 2006 she was transferred to Reef HQ Aquarium in Queensland, Australia where she met her mate. By 2008, she had started laying eggs and the pair had multiple litters of offspring through sexual reproduction. After her mate was removed from the tank to prevent further breeding, she has shared the tank with […]

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Ammonia tolerance of goldfish

Liver failure or congenital defects can lead to a build-up of ammonia in the brain of mammals resulting in life-threatening swelling, convulsions and comas. For goldfish (Carassius auratus), environmental exposure to ammonia causes reversible swelling of the brain. In a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers wanted to explore how the fish were able to accomplish this. They exposed goldfish to high […]

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Why orcas go through menopause

Orcas are one of only three species of mammals that go through menopause, including humans of course. A new study published in Current Biology may have discovered why this happens in killer whales. Examination of 43 years worth of data collected by the Center for Whale Research and Fisheries and Oceans Canada, revealed a remarkable finding about the costs of reproduction in orcas. Older mothers tend to spend more time taking care […]

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The obese marathon mouse

As the name implies, Dummerstorf marathon mice are bred to run. If allowed to be sedentary, these animals can build up quite a bit of fat within their peripheral tissues even if they do not overeat. If given an exercise wheel, however, they burn fat very quickly. In a new study published in the Journal of Comparative Physiology – B, researchers discovered that the livers of these mice have an increased ability to not only […]

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Pigeons can identify words

A study recently published in the Proceedings of the National Academy of Sciences provides evidence that pigeons can learn to recognize words. That is after the birds were trained over a period of 8 months. According to the study authors “The pigeons’ performance is actually more comparable to that of literate humans than baboons’ performance.” To read, we must be about to decode letters and the sounds they make as […]

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Carbon monoxide lowers breathing rate in fish too

  We tend to think of carbon monoxide (CO) only in terms of being a poisonous gas. The reason for its toxicity is due to its ability to bind really tightly to our hemoglobin molecules, which prevents oxygen from being able to bind. In mammals, CO also decrease breathing rate. As you can imagine, it is a pretty terrible gas to breath in when you are a species dependent on hemoglobin for delivery […]

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